Radio receiving system



July 5, 1932. M a B'A L 1,865,426

I RADIO RECEIVING SYSTEM Filed Oct. 30, 1928 INVENTOR Max C. Bafse/ 1/ ATTORNEY Patented July 5, 1932 5; F re a We a :3 i i,

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MAX 0. BATSEL, OF VJILKTNSB'JRG, PENNSYLVANIA, AS$IG-NOB 'IO WESTINGHOUSE lilLilCTRIlC 8: MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA HADES RECEIVING: SYSTEM .ilpplication filed October 30, 1928.

. d1ant energy.

In one modification of my invention, I employ an aerial or other radio receptor, a radio-frequency amplifier and a detector, all of which are well known in the art. In combination with these elements, I use a special arrangement of the output circuit of the amplifier which will permit the transfer therefrom of energy to later circuits in response to received signals, and which, in addition, tends to stabilize this said amplifier against oscillation.

lVhen the stage of a receiving system adj acent to the radio receptor oscillates, and causes the receptor to radiate energy, another receiver nearby may be seriously interfered with if an attempt is made to receive on it signals of approximately the same wave length as those to which the receiving system is tuned. Such interference in receiving is, of course, very objectionable, and my invention provides means whereby certain stages of a receiver may be operated regeneratively, if desirable, without causing earlier stage to oscillate.

The novel features that 1 consider char acteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its rganization and its method of operation, together with further objects and advantages thereof, will best be understood by reference to the following description, taken in connection with the accompanying drawing.

Figure 1 is a diagrammatic View of a radio Serial No. 316,067..

receiving system comprising a preferred embodiment of my invention, 7

Fig. 2 is a diagrammatic view of a radio receiving system of an alternative type embodying my invention.

The receiving system illustrated in Fig. 1 comprises a receptor circuit consisting of an aerial 1, a condenser 2, an inductor 3 and a ground connection 4. The secondary winding 5 of an amplifying transformer 6 is serially included in the receptor circuit and has a bypass condenser 7 connected in shunt thereto.

An amplifier triode 8, having a grid 10, a filament 11 and a plate 12, is so disposed with reference to the receptor circuit that the grid may be energized therefrom through a conductor 13.

The output circuit of the triode 8 comprises an inductor 14, the primary 15 of an amplifying transformer 16, and a source 17 of plate potential, the negative terminal of which is connected to the filament 11 through a bus-Wire 18. The primary winding 15 has a condenser 19 connected in shunt thereto for a purpose which will later be described. The negative terminal of a source 20 of filament potential is also connected to the buswire 18, the positive terminal of the source 20 being connected to a second bus-wire 21 to which the filament 11 is also connected.

The inductor 14 is coupled to an inductor 22 which is included between the grid 23 and filament 21 of a thermionic triode 25, and

which has a tuning condenser 26 connectedv in shunt thereto. In the specific example chosen for illustration, the triode is provided with a grid-leak 27 and grid-condenser 28, and functions as a detector, although my invention is equally well applicable if a second amplifier triode is utilized instead of the detector.

The filament 2 1 of the triode 25 is provided with energizing potential from the source 20 through the bus-wires 18 and 21, being connected thereto in parallel with the filament of the triode 8.

The output, or plate, circuit of the triode 25 comprises a feed-back inductor 30, the primary winding 31 of the transformer 6, and

the source 17 of plate potential. A by-pass condenser 32 is connected in shunt to the primary winding 81 and the potential source 17, and serves to conduct energy at radio frequency around them.

The secondary winding 33 of the amplifying transformer 16 is connected between the grid 34 and the filament of an amplifying triode 36, the filament connection being made through the bus-wire 18 which supplies filament power to the said triode. The output, or plate, circuit of the triode 36 comprises a sound-producing device, such as a pair of telephones 37, or a loud-speaker (not shown) and the source 17 of plate potential.

A rheostat 38 may be provided in the common filament-power supply-circuit, if desirable, or each of the triodes may be provided with an individual rheostat.

In the operation of the system just described, the incoming radio-frequency oscillations are amplified in the triode 8 and are impressed upon the tuned input circuit of the triode 25 through the transformer comprising the inductors 1A and 22. The triode 25 rectifies the oscillations impressed thereon, and its output, as audio'frequency, is impressed on the input circuit of the triode 8 through the transformer 6.

The triode 8, being thus additionally energized by an audio-frequency, input, has an output current proportional both to the incoming radiofrequency and to the said audio-frequency energization. The audiofrequency component of the output current is impressed, through the transformer 16, on the input circuit of the amplifier triode 26, which triode accordingly produces an ainplified output sufficient in magnitude to energize the sound-producing device.

y reason of the fact that the output circuit of the triode 8 contains the inductor 1-1 coupled to the tuned input circuit of the triode 25, the first mentioned triode has a tendency to oscillate. The tendency toward oscillation of the triode 8, occasioned by the inductive reactance of the plate circuit, I have discovered, can be counteracted by the introduction of the proper amount of capacitive reactance in the said circuit. I have, accordingly, so chosen the size of the shunting condenser 19 that the inductive reactance of the plate circuit is overcome, thus greatly lessening the tendency of the triode toward oscillations by controlling the phase relation between the plate current and the grid excitation thereof.

The triode 8, therefore, transmits energy readily from the receptor circuit toward the amplifier triode 36, but, by reason of the fact that it does not readily oscillate, it will not transfer an appreciable amount of energy toward the receptor circuit even in the event that the detector triode 25 is caused to oscillate by the tickler coil 30.

nsea42e Fig. 2 shows aslightly different disposition of parts in a similarly operating system. The same elements are used as in Fig. 1. The difference between the two arrangements is in the position of the audio-frequency transformer 6. In Fig. 2, this transformer is connected between the aerial tuning inductance 3 and the grid of triode 8, instead of being connected in the ground lead 4.

In the position shown in Fig. 2, audiofrequency energy is transferred to the grid of triode 8, equally as well as in the position shown in Fig. 1, with the additional advantage that the aerial circuit is not blocked to audio-frequency impulses by the inductance of the primary winding. This allows such inductive impulses as 60 cycle induction from power wires near to the aerial, or are discharges, to pass to ground without affecting the receiver circuit.

Although I have shown my invention as applied to the output circuit of an amplifier which is inductively coupled to the tuned input circuit of a regenerative detector, it will be apparent to those skilled in the art that the invention is not restricted to the specific embodiment chosen for illustration. The regenerative detector may well be a second amplifier triode, and the reflex feature may be entirely divorced from the receiving system. In other words, it is my impression that I am the first to compensate the inductive reactance of an amplifier output circuit over a definite tuning range by the inclusion, in such a circuit, of sufiicient capacitive reactance, either in the form of a coil having a high inter-turn capacity or in the form of a coil shunted by a condenser, to compensate the said inductive reactance, whereby the amplifier is prevented from oscillating.

My invention, therefore, is not to be limited except insofar as is necessitated by the prior art or by the spirit of the appended claims.

I claim as my invention:

1. A radio receiving system comprising a plurality of thermionic triodes connected in cascade relation, said connecting means being so proportioned that one of said triodes tends to oscillate when receiving signals over the range of frequencies for which the systern is intended, and means comprising a capacitor included in series with a portion of said connecting means for compensating said tendency toward oscillation.

2. A radio receiving system comprising a triode having input electrodes associated with a tunable circuit, an output circuit comprising an inductor the reactance of which is inductive over the range of tuning of said input circuit, and means serially included in said output circuit for compensating said inductive reactance, whereby the output circuit as a whole is not sufliciently inductive to render the said triode oscillatory to frequencies included in said range,

3. In a radio receiving system, an in tertube energy-transferring network comprising a primary winding, a secondary winding inductively coupled thereto, means for tuning said secondary Winding over a predetermined frequency range, and additional means for rendering the reactance of said primary winding predominately capacitive to the frequencies embraced in said tuning range.

4:- In a radio receiving system, a plurality of thermionic triodes, coupling means between at least two of said triodes, said coupling means comprising a primary winding included in the output circuit of one of said triodes and a secondary winding included in the input circuit of the other of said triodes, the reactance of said primary winding being inductive over the range of frequencies to which the secondary winding is tunable, and means serially included in said output circuit for compensating said inductive reactance, whereby the said output circuit, when considered as a whole, is not sufficiently inductive to render the said triode oscillatory over the range covered by said tunable secondary.

5. In a system for efficiently amplifying high-frequency electrical currents, the combination of a. three-electrode-vacuum-tube amplifier having inherent capacity between its electrodes, means for energizing said tube to operate as an efficient amplifier, a high-freuency tunable circuit connected to the input e ectrodes of said amplifier, a second threeelectrode vacuum tube having a tunable circuit in its input circuit adapted to be varied in consonance with said first tunable circuit, said second circuit being so closely coupled with the out-put circuit of said first tube to efficiently transfer energy therefrom that its transient reactions on said output circuit in the operation of varying it to follow said first tunable circuit inevitably include that reaction which unmodifiably acting through said inherent tube capacity is of such phase and potential as to cooperate with said first tunative action, and means permi ing m i i i id @1056 oupling between said circuits and said efiicientamplification of said tube hil reventing said oscillation including impedance means associated with a circuit of said first tube for modifying the eifect through said inherent capacity of said coupling reaction to sufficient degree that said second circuit may be varied at will unaccompanied by oscillation production.

6. In a system for eiiiciently amplifying high-frequency electrical currents, the combination of a three-electrode-v'acuum-tube amplifier having inherent capacity between its electrodes, direct-current means for enerable circuit to produce oscillation by regene'r gizing plate and filament electrodes of said tube to operate as an efficient amplifier, a high-frequency tunable circuit connected to the input electrodes of said tube, a second three-electrode vacuum tube having a tunable circuit in its input circuit adapted to be varied in consonance with said first tunable circuit, said Second circuit being so closely coupled with the output circuit of said first tube for efficiently transferring energy therefrom that its transient reactions on said output circuit in the operation of varying it to follow said first tunable circuit inevitably include that reaction which unmodifiedly 'acting through said inherent tube capacity is of such phase and potential as to cooperate With said'first tunable circuit to produce oscillations by regenerative action, and means permitting maintaining said close coupling between said circuits and said efficient amplification of said tube while preventing said oscillations including conductive impedance means associated with a circuit of said first tube for modifying the effect through said inherent capacity of said coupling reaction to sufficient degree that said second circuit may be varied at will unaccompanied by oscillation production and the tube electrode in said circuit may be energized by a direct current potential.

7. In a system for efficiently amplifying high-frequency electrical currents, the combination of a three-electrode vacuum tube amplifier having inherent capacity between its electrodes, a tunable high-frequency circuit connected to the input electrodes of said tube, connections for operating said tube as an efiicient amplifier, a second three-electrode vacuum tube having a tunable circuit in its input circuit adapted to be varied in consonance with said first tunable circuit, said second circuit being so closely coupled with the output circuit of said first tube to efficiently transfer energy therefrom that its transient reactions on said output circuit in the operation of varying it to follow said first tunable circuit inevitably include that reaction which unmodified-1y acting through said inherent t ube capacity is of such phase and potential as to cooperate with said first tunable circuitv to produce oscillation by regenerative action, means for overcoming a desired degree of sald regenerative action while permitting maintaining said efficient amplification and said close coupling between said circuits whereby said second circuit may be varied at Wlll unaccompanied by oscillation produc tion, and means for operating said second tube as a stable amplifier of the currents delivered thereto. r

8. In a system for efficiently amplifying high-frequency electrical currents, means for the multiple amplification of said currents including the combination of a threeelectrode vacuum-tube amplifier having in- 'h'erent capacity between its electrodes, a

' varied in consonance with said first tunable circuit, said second circuit being so closely coupled with the output circuit of said first tube to efficiently transfer energy therefrom that its transient reactions on said output circuit in the operation of varying it to follow said first tunable circuit inevitably include that reaction which unmodifiedly acting through said inherent tube capacity is of such phase and potential as to cooperate with said first tunable circuit to produce oscillations by regenerative action, means for returning amplified energy from the output circuit of said second tube to said second tunable circuit in degree sufficient to cause saidsecond tube to selectively increase its amplifying ability without generating oscillations, but resulting in an intensified reaction of said second tunable circuit on the output circuit of said first tube, and means for preventing said first tube from generating oscillations while maintaining said close coupling in the presence of said regenera tive action in said second tube, whereby both tubes function as efficient and stable amplifiers of the same selected high-frequency current;

9. In a system for efliciently amplifying high-frequency electrical currents, means for the multiple amplification of a selected frequency current including a pair of threeelectrode vacuum tube amplifiers, a selective circuit connected to the input electrodes of one of said tubes, couplings linking the output circuits of both of said tubes to said selective circuit whereby it performs the dual function of simultaneously selectively increasing the amplifying ability of both of said tubes, and means associated with both of said tubes for limiting the degree of said selective increase of amplifying ability whereby both of said tubes function as stable amplifiers.

10. In an amplifier of high frequency electrical currents, the combination of a threeelectrode vacuum amplifier having inherent capacity between its electrodes, a tunable circuit in the input circuit of said amplifier, a second three-electrode vacuum tube having a tunable circuit in its input circuit adapted to be varied in consonance with said first tunablec'ircuit, said second circuit being so reactively associated with the output circuit of said first tube to efiiciently transfer energy therefrom that its transient reactions on said output circuit in the operation of varying it to follow said first tunable circuit inevitably include that reaction of inductive nature which unmo'difiedly acting through said inherent tube capacity produces oscil' lation by regenerative action, and a capacitively reacting element associated with said output circuit to alter the overall reaction thereof to sufiicient degree to prevent said *oscillationproduction while maintaining? amplifier, a second three-electrode vacuum tube having a tunable circuit in its input circuit adapted to be varied in consonance with said first tunable circuit, said second circuit being so reactively associated with the output circuit of said'first tube to efiicicntly transfer energy therefrom that its transient reactions on said output circuit inevitably include that reaction of inductive nature which ,unmodifiedly acting through said inherent tube capacity produces oscillation by regenerative action, and means for preventing said oscillation production While maintaining said efiicient coupling comprising a reactance element so connected in said output circuit as not to prevent the flow of:

direct current therein but presenting a reaction to all the current frequencies adapted to be selected by said tunable circuits that is sufliciently capacitive to oppose said inductive reaction to adequate degree to modi- MAX G. BATSEL.

of high-frequency 

